Hmm, I believe I've seen shades of this idea in Selenium's most basic test script format [1]. It isn't a decision table, per se, but it was designed to be as easy as possible for non-programmers to adjust. That said, I don't think table-driven programming is as widely useful as this author claims. Most of the testing engineers I know immediately moved away from Selenium script tables toward higher level constructs in JavaScript or Python. I don't think a table is great for expressing recursion or iteration.
I think tables can work great for expressing such concepts, but Sturgeon's Law applies here, too: almost all table-based systems do it badly. Subtext has no problem with recursion.
Very cool, I did not know that somebody had already gone and made a programming language like this. In watching the first ~10 minutes of the demo video [1] my thoughts were "Yes, this is a perfect example of where a table could be better than if/else," then when the warning indicators popped up at 5:50 "hmm, boolean algebra is still hard," and then at 7:30 with the demo of fibonacci/recursion "exploded expression trees that must be manipulated by mouse... let's go shopping."
But still, a lot of interesting thinking went into something like this, and it makes you wonder if it would be appropriate to "embed" a similar interface into an IDE for manipulating complex switch case/elseif chains.
[1] http://seleniumhq.org/docs/02_selenium_ide.html#test-suites